Thomas Cook had three A321s based at BRS in summer, athough one was replaced by a 320 for part of the season in a pre-planned move, and one A321 in winter. Thomas Cook handled about 500,000 passengers annually at BRS in recent years so that's a fair chunk out of a near 9 mppa throughput. With flybmi calling it a day in February it's not been the best of years for BRS although growth this year will still likely to be around 200,000+ which is still a far cry from the 2.4 million added in the previous four years.
Given the wealthy nature and propensity to travel of much of the immediate city region and West Country in general it might be surprising if some of the TCX void is not replaced by someone. Who that someone might be is far more difficult to determine. The only obvious gesture so far is Ryanair adding a fourth weekly Malta rotation next summer following Thomas Cook's absence on the route - Air Malta also seems to have gone.
Ryanair's Laudamotion announced a Vienna route for next summer but that will compete with easyJet's existing route which is year-round and that's the total of recent route announcements.
2020 is likely to be just the sixth calendar year since 1970 that BRS will have seen a drop in annual passenger numbers against the prevous year, although until the 1980s annual passenger throughput was in low six figures.